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Old 05-17-2003, 04:43 PM   #1
Minion
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Default True or False?

Its it true that CAI is bad for a stock wrx?
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Old 05-17-2003, 06:42 PM   #2
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Old 05-17-2003, 07:27 PM   #3
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I don't think that is bad for what it is just that the stock ECU and sensors can't properly read whats going on and the effects of the CAI are lost. That is my understanding. Plus the stock intake is fairly good.
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Old 05-17-2003, 07:45 PM   #4
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Ture. Causes improper MAF sensor readings, causing improper fueling from the stock ecu.
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Old 05-17-2003, 07:53 PM   #5
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Would a cobb ecu flash fix the problem?

Also wondering how bad it actually is....I have one on my w right now, and Ill take it off asap if it is "urgent bad"

Stupid MAF!!
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Old 05-17-2003, 08:30 PM   #6
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I will be getting my Cobb reflash real soon, hopefully this week, I don't think they have a map for it, but if you go there and get a dyno tuning I am sure it would be fine.

As for "urgent" need to take it off, I am not the right person to know. But it would probably be wise to take it off until the ecu can properly read it.
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Old 05-17-2003, 09:13 PM   #7
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Ok this is for everyone. There are two things count em 2 things you don't need on your WRX if your not making more then 300HP a Blow-off valve, and a intake of any kind. what happens is with a CAI there is more air going in and the MAF does not know that so your getting the same amount of gas and then thats where the bad stuff is you are now running lean to much air not enough gas. So unless you have a computer that knows that. You should not have one. Besides they are to loud. Save your money and get a Exhaust or a Down Pipe. Hope that helped. THE END


Brandon
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Old 05-18-2003, 06:15 PM   #8
hoodwho
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yup CAI=waste of $$
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Old 05-18-2003, 07:53 PM   #9
Minion
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Now I know that CAI is a waste. But is it an immediate threat to my car? And will a ecu flash fix the problem, or are there any aftermarket MAF chips?
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Old 05-18-2003, 11:44 PM   #10
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One more time if your not making more then 300hp take it off its a waste of space and no the Cobb reflash will not fix that unless you get it dynotuned. And yes it could be doing damage. your 3rd cylinder runs hot already and that intake might cause more problems. take it off and just get a K&N filter. Once again aftermarket intake bad got it good. THE END
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Old 05-18-2003, 11:56 PM   #11
Minion
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Thank you for answering my question supersonic. I simply needed to know if I need to make time asap to take it off, or if it could wait a week. I also was wondering about the ecu flash, because I wanted to see if I could find a way to keep the intake...seeing that I spent money on it already, and I like the sound of it. But again, thanks for answering the questions.
And, thank you to everyone else who did as well.

Minion
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Old 05-19-2003, 12:06 AM   #12
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Its not something that needs to come of tonight or tomorrow its more of a take it off when the weekend comes around kinda thing. The only CAI that I've seen not do any damage or hurt the car in any way would be the perrin CAI. You might wanna look into that or like I said get a downpipe. That said I did put a Blow off valve on the second I got the car. THE END


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Old 05-19-2003, 12:08 AM   #13
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You could be running too lean

Your engine could be damaged by using a CAI

It may

It may not

It's up to you to take the risk...
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Old 05-19-2003, 12:14 AM   #14
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Default Not urgent

I think your CAI is not an important issue until it gets really hot out. Here at altitude we are running less effective boost and the fuel system has a little more head room to accomodate lean conditions. Things that would be a big problem at sea level are not always something to worry about up here. Just take care if you make a run to lower elevations before you get properly tuned for the changes.

The CAI intake will lean out the mixture slightly but unless you beat on the car hard it should not be a major issue. Just avoid long hard pulls at high rpm in 4th and 5th gears. The rpm range above about 5700 rpm has no knock protection as the ECU does not listen for it at those rpms, and high load in the upper gears can lead to fatal detonation damage to the engine.
If you have no intention of running WOT under heavy load you will probably not have any problem with that intake.

The ECU will compensate for it in closed loop conditions over time, so your mixture under cruise conditions will be completely normal. But at WOT when it is running open loop it might run you lean enough to cause engine damage under the conditions I mentioned above.

Just be careful to run an adequate octane fuel. If it gets up in the 90's before you get things adjusted, I'd suggest you invest in a bit of insurance and spike your fuel with some high octane.

As far as the reflash, no doubt a dyno tune would be prefereable, but I'm sure Cobb has seen enough CAI intake cars to be able to tweak the setting enough to compensate.

You might want to just give the guys at Cobb's a call they can give you some authorative answers to what they can and cannot do with a remote reflash without time on the dyno.

Larry
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Old 05-19-2003, 12:18 AM   #15
Minion
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Im not sure its worth the risk. Again I LOVE the sound, I can actually hear the turbo and spit. But not worth damage thats forsure.
With out a doubt I am getting Upipe/Downpipe/Exhaust. Currently doing research on which to get now.
Thanks again

Minion
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Old 05-19-2003, 12:26 AM   #16
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Larry,
Great info! Thank you. Seeing that I drive to Las Vegas during summer/winter months, I think it might be wise to remove it seeing that its 110+ degrees during summer. I will also give COBB a call as you suggested. Thanks.

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Old 05-19-2003, 10:37 PM   #17
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Does removing the resonator and replaciing the stock filter with a K&N pose the same risks as adding a CAI? If not, why?

Tim

Last edited by Timmay; 05-19-2003 at 10:44 PM.
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Old 05-19-2003, 11:28 PM   #18
hotrod
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Default Shouldn't be a problem

The problem with most of the CAI is the size of the tubing. The stock MAF sensor is calibrated for the stock intake tube diameter. It measures the airflow speed and temperature, from those two pieces of info the ECu computes how much air could flow through the stock intake tube and sets your fuel accordingly.

The CAI usually have a 3 inch tube dia which has about a 20% larger throat area, so a given speed of flow in the CAI will actually flow about 20% more air that the ECU predicts.

In closed loop operation, ie. just cruising around, the ECU will figure out the difference and slowly add trim to the fuel injector pulse width until the mixture is right at low throttle openings. At high throttle openings it does not adjust the same way being in open loop it just runs off the mixture maps it has in memory, and that can lead to lean out at high rpm.

Depending on conditions you get a high power lean mixture which is good for performance or you push it over the edge a bit and start getting high EGT's and detonation. Each engine is a little different here as is the way different folks drive.

One person may only do quick blasts of high rpm highload operation infrequently and get away with the lean conditions for a long long time. Another person may try to get to 160 mph and pull in a high gear for a long time or load the car down with 4 big friends and try to pass a truck on a steep hill and kill the motor due to detonation.

Larry
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Old 05-20-2003, 12:13 AM   #19
Minion
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Default Re: Shouldn't be a problem

Quote:
Originally posted by hotrod

The CAI usually have a 3 inch tube dia which has about a 20% larger throat area, so a given speed of flow in the CAI will actually flow about 20% more air that the ECU predicts.
Larry
Ok, I guess the question I have to that is....
Why not build a CAI that isnt 20% larger, but just simply less restrictive then the stock intake?

Or am I not seeing the point here?
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Old 05-20-2003, 12:49 AM   #20
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Default Re: Re: Shouldn't be a problem

Quote:
Originally posted by Minion


Ok, I guess the question I have to that is....
Why not build a CAI that isnt 20% larger, but just simply less restrictive then the stock intake?

Or am I not seeing the point here?
That would work.

TurboXS shorty and Perrin short ram intake have the stock size MAF tube. So they don't cause the common known problems.

i don't know of a CAI though....
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Old 05-21-2003, 07:01 AM   #21
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I feel like a complete idiot noob as I'm posting this. I installed the AEM CAI well before learning of this site and reading about the dangers of an aftermarket cold air intake. I'll admit I got ants in the pants and just wanted to add a mod to the car, and everyone I talked to said an intake was a good first choice (very wrong it seems).

I've read through the thread and learned some valuable information, but I guess I'm just trying to figure out a way to leave the damn thing on. The bad news is, I no longer have the stock intake and I can't return the AEM. I fill my tank with 94 octane fuel and I push my car past 90 maybe once a year and never over 110. I bought an EGT gauge and will have it installed by the weekend. Is there anything I can do to leave it on, or will my motor eventually blow up?

Thanks for helping a newb, and for the wonderful info.
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